linux-kernel - Re: [RFC PATCH 5/9] kvm_main.c: split __kvm_set_memory_region logic in kvm_check_mem and kvm_prepare

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Message-ID: <b9e8febd-b87e-422c-fc67-59272d225e1d@redhat.com>
Date:   Sun, 18 Sep 2022 18:22:12 +0200
From:   Emanuele Giuseppe Esposito <eesposit@...hat.com>
To:     "Yang, Weijiang" <weijiang.yang@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        David Hildenbrand <david@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [RFC PATCH 5/9] kvm_main.c: split __kvm_set_memory_region logic
 in kvm_check_mem and kvm_prepare_batch



Am 13/09/2022 um 04:56 schrieb Yang, Weijiang:
> 
> On 9/9/2022 6:45 PM, Emanuele Giuseppe Esposito wrote:
>> Just a function split. No functional change intended,
>> except for the fact that kvm_prepare_batch() does not
>> immediately call kvm_set_memslot() if batch->change is
>> KVM_MR_DELETE, but delegates the caller (__kvm_set_memory_region).
>>
>>
>> +static int kvm_check_memory_region(struct kvm *kvm,
>> +                const struct kvm_userspace_memory_region *mem,
>> +                struct kvm_internal_memory_region_list *batch)
>> +{
>> +    int r;
>> +
>> +    r = check_memory_region_flags(mem);
>> +    if (r)
>> +        return r;
>>   -    r = kvm_set_memslot(kvm, batch);
>> +    r = kvm_check_mem(mem);
>>       if (r)
>> -        kfree(new);
>> +        return r;
>> +
>> +    r = kvm_prepare_batch(kvm, mem, batch);
>> +    if (r && batch->new)
>> +        kfree(batch->new);
> From the patch, r !=0 and batch->new !=NULL are exclusive, so free()
> here is not reachable.

Good point, I'll get rid of this.

Thank you,
Emanuele
>> +
>>       return r;
>>   }
> [...]
>>   
>